In plain words
For one who has conquered oneself and is serene, Paramātma is present as one's very self; such a one should remain the same through cold and heat, pleasure and pain, honour and dishonour.
Word for word
Of one who has conquered himself, the serene, the supreme Self [is] present; in cold and heat, pleasure and pain, likewise in honour and dishonour [he should be the same].
जितात्मनः प्रशान्तस्य परमात्मा समाहितःशीतोष्णसुखदुःखेषु तथा मानापमानयोः
Other commentaries
The commentators
▸Bhagavadgītābhāṣyam· bhāṣya
जितात्मनः कार्यकरणसङ्घात आत्मा जितो येन सः जितात्मा तस्य जितात्मनः, प्रशान्तस्य प्रसन्नान्तःकरणस्य सतः संन्यासिनः परमात्मा समाहितः साक्षादात्मभावेन वर्तते इत्यर्थः । किञ्च शीतोष्णसुखदुःखेषु तथा माने अपमाने च मानापमानयोः पूजापरिभवयोः समः स्यात् ॥ ७ ॥
In plain words
Jitātmanaḥ — "one whose self is conquered." The "self" here is the bundle: body, senses, inner organ, the whole assembled thing you ordinarily call yourself. Whoever has brought that under him is jitātmā, and it is of such a man that the verse speaks — a man wholly quieted, his mind gone clear as still water, a saṃnyāsin. For him the supreme Self is samāhita, firmly established: it abides directly, with nothing in between, as his own very being. That is the meaning. And more: in cold and heat, in pleasure and pain, and equally in honour and dishonour — in being venerated and in being insulted — he is to be the same.
Close to the Sanskrit
Jitātmanaḥ: the aggregate of the body (effect) and the senses (instruments) is the 'self'; he by whom that self has been conquered is jitātmā; of him, of that one whose self is conquered — of one who is wholly quieted, whose inner organ is clear, being a saṃnyāsin — the supreme Self is firmly established, that is, it abides directly as his very own being: this is the meaning. Moreover, in cold and heat, in pleasure and pain, and likewise in honour and dishonour — in the pair honour-and-dishonour, that is, in being venerated and in being insulted — he should be the same.